In a summer punctuated by horrifying incidents of children dying in hot cars, one state will now allow bystanders to break into a car if they see a kid inside who they believe is in danger.

As of July 1, you can legally smash a window or otherwise forcibly enter a parked car in Tennessee without liability if you have “a good faith belief” the actions help a minor who will suffer “harm if not immediately removed from the vehicle.”

State Rep. David Hawk, who sponsored the bill, called it a landmark piece of legislation.

“But if that does occur in Tennessee, I want our citizens to be aware that they have the ability to take action, to be a Good Samaritan and to save that child without fear of repercussions.”

Last year, 44 children in the U.S. died of heatstroke in cars, according to KidsandCars.org. That grim tally has reached 16 so far this year, including the high-profile case of Cooper Harris, the 22-month old found dead in the family SUV in suburban Atlanta last month. His father has been charged with murder.

While other states have broad laws that protect Good Samaritans from lawsuits, the Tennessee law is unique in that is specifically addresses kids left in cars, said Janette Fennell, founder and president of KidsAndCars.org, a nonprofit child safety organization.

She hopes more states follow suit.

“I think it’s fantastic because many times people are faced with this situation where they might see a small child in a car and think, that’s not my business, I don’t want to get involved,” Fennell said. “When it comes to children, we should all be comfortable with getting involved.”

Because of the danger, Fennell advises people to be proactive, and look inside parked cars whenever they walk through a parking lot. If you spot a child alone inside a car, call 911 immediately, she recommends. If the child looks in serious distress, check to see if there’s any way to get into the car and if not, try to figure out which window you could break so the glass doesn’t harm the child, she added.

Not everyone agrees.

Lenore Skenazy, author of the book "Free-Range Kids" and blog of the same name, thinks calling 911 the moment a child is spotted alone in a car is “lunacy.” She advises people to stand by the car for a while and wait for the parent to return to determine if the child has actually been forgotten there.

“We have become so sensitized to the danger of kids waiting in cars, we can no longer see the difference between a child waiting while mom gets the pizza and a child locked in the car all day long. But there is a big difference,” said Skenazy.

When parents are running errands, sometimes it doesn't make sense to bring a child inside the store with them, so families should be allowed to make that choice, Skenazy noted.

“Most of us waited in the car as kids — often. That practice simply had not been labeled negligence back then because it wasn't, and isn't. It's a decision that decent, rational parents who love their kids make every day,” she said.

Fennell countered that's never OK.

“People need to step back for a second and say: ‘Would I leave a million dollars in my car?’ I think the answer to that would be, absolutely not,” she said.

Nineteen states now have laws that specifically make it illegal to leave a child unattended in a vehicle, according to KidsAndCars.org.

Experts warn children can get dangerously hot quickly when left alone in a car. Heatstroke can happen when the temperature is as low as 57 degrees outside and cracking a window does little to keep the car cool, according to SaferCar.gov.

Before using force, the new Tennessee law requires people to first call 911 and make sure there’s no other way to get inside the car, like an open door, sunroof or window. If force is required, you must leave a note on the car windshield with your contact information, the reason for the break-in and the location of the child.

There’s no protocol in the new law for how a concerned citizen should forcibly enter a car — just whatever works at that particular moment, Hawk said.